We consider a lower weight better because lighter devices are more comfortable to carry. A lower weight is also an advantage for home appliances, as it makes transportation easier, and for many other types of products.
We consider a thinner chassis better because it makes the product more compact and portable. Thinness is a feature highlighted by many manufacturers of mobile devices, but it is essential for a wide range of products.
One of the most important aspects to pulling a great espresso is the amount of pressure used. Aspects such as how tightly tamped the portafilter is can affect the pressure and therefore the overall quality of the extraction. A pressure gauge helps you to adjust your process to achieve a perfect 9 bar of pressure.
A PID controller controls the temperature of the boiler electronically. It offers a far greater degree of accuracy and consistency than a regular, mechanical thermostat used to control temperature. This is very important as a temperature of around 92°C to 96°C is key to pulling the perfect espresso.
At the end of the extraction process, all moisture is removed from the puck. This allows you to easily tap out the coffee from the portafilter afterwards, reducing mess and the need to clean it as often.
A 3-way solenoid valve relieves the portafilter of pressure and moisture after the extraction. This produces a dry puck which can easily be removed afterwards. It also means that you don’t have to wait for the pressure to equalise, so that you can make back-to-back coffees.
With a pre-infusion function you get a low pressure of water before it ramps up to around 9 bar of pressure. This gently expands the grinds to get a smooth extraction and to help prevent channeling in the cake.
With a double boiler or heat exchanger system, you can brew and steam milk at the same time. This has an advantage over single boiler machines where you have to wait between brewing and steaming for the temperature to adjust.
These buttons can be programmed for different types of coffee such as an espresso, doppio or ristretto. This means once you have mastered a particular style of coffee, you can get it the same every time.
The time taken to pull an espresso shot is one of four key elements, and should be around 19-22 seconds. Once you have the grind, dose and tamp correct, you can use the shot clock to time the pull perfectly.
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A higher number of grind settings gives you more flexibility when choosing the fineness of your ground coffee. The particle size is important as a grind which is too coarse can produce weak tasting espresso, whereas a grind which is too fine can lead to a bitter taste.